Researchers at the University of Bristol Dental School have found these teas erode the enamel or protective layer on teeth.
Some are even more harmful than orange juice, which is very acidic and is known to harm teeth.
The researchers said the findings should act as a warning to people who regard herbal teas as a healthy alternative to other drinks.
Writing in the Journal of Dentistry, the researchers said: “Many epidemiological studies show a high prevalence of tooth wear, even in young patients.
“One factor that may be contributing to this problem is the consumption of herbal teas that are often considered to be ‘healthy’ alternatives to other beverages.”
The researchers measured the acidity of a range of teas and found wide variations. Some had low pH levels – indicating high acid levels – while others were relatively alkaline and harmless.
Overall, the researchers found that many of the teas eroded tooth enamel. Some were three times more damaging than orange juice.
Dentists generally advise against drinking too much fruit juice. The sugars in these drinks are known to cause teeth erosion.
“Dentists who treat patients with tooth erosion should advise them against drinking herbal tea. This information will be of use to clinicians when counseling patients with tooth surface loss”, the researchers wrote.